The present invention relates to a unit for supporting the axle-shafts of go-karts.
In particular, the present invention regards a supporting unit referred to as “Y unit” and normally comprising:                an adjustable support defined by an annular body provided with a concave seat having an axis of adjustment, and with a radial slit made in a plane transverse to the axis of adjustment itself;        a ball bearing having an axis of rotation transverse to the axis of adjustment and comprising an outer ring, which is provided with a convex outer surface, and is mounted within the concave seat with the possibility of adjustment about the axis of adjustment; and        a tightening element, which comprises a tangential screw set through the radial slit, and is designed to tighten the support on the bearing in order to block the bearing itself in an operative position.        
Y units of the type described above are able to compensate for possible initial errors of alignment given that the bearings inserted in the supports can allow a moderate initial misalignment about the axis of adjustment, and are advantageously used for supporting the axle-shafts in go-karts, considering also the simplicity and economy of the systems that can be obtained with the Y unit itself.
In this application, once the bearing has been set in its own operative position, in which the axis of rotation of the bearing is aligned to the axis of rotation of the axle-shaft, the sharp and sudden stresses to which the axle-shafts themselves are subjected can cause, irrespective of the magnitude of the tightening force, the possible misalignment of the bearing within the support, without, however, any possibility of an automatic return of the bearing itself into its proper operative position.
Said misalignment reflects on the entire axle-shaft and on the capacity of the respective wheel to transmit the torque to the ground, i.e., in other words, said misalignment leads to a loss in performance of the go-kart, which can be remedied by resetting the bearing again in its operative position. Said latter operation can be carried out only with the go-kart stationary and, in any case, with also the risk of forcing the support too much on the bearing, with harmful consequences on the optimal operation of the entire Y unit.
In general, in the field of bearings, tightening elements are already known, which, in order to increase the capacity of gripping between the bearing and the corresponding support, have one or more recesses of various shapes made either on the outer surface of the outer ring of the bearing, or else on the inner surface of the concave seat to exploit the tendency of the metal material of the softer part, in general that of the support, to undergo deformation following upon tightening of the support on the bearing.
A significant example of embodiment of said recesses is known, for example, from the European patent application No. EP 1 347 189, which describes an improved seat for bearings that is able to increase tightening between the two parts, providing one of the two parts with surface irregularities and making the other part with a softer material.
In particular, in the European patent application No. EP 1 347 189 it is described how the outer surface of the outer ring of the bearing has a plurality of axial irregularities, which, during tightening, cut into the softer inner surface of the support, consequently increasing the grip between the bearing and the support, avoiding the need both to resort to very restricted tolerances and to resort to auxiliary accessories.
From the European patent application No. EP 1 347 189, it is evident that the axial irregularities, i.e., the ones made parallel to the axis of rotation of the bearing, have the primary function of increasing the interference in mounting of the bearing in the seat and of preventing a relative rotation of the outer ring and of the seat about the axis of rotation of the bearing itself.
However, in the case where the outer ring of a Y unit for axle-shafts of go-karts were provided with the same axial irregularities it would not be able in any case to counter effectively the above-mentioned stresses and consequently would not be able to prevent misalignment of the bearing from its own operative position